Circulating glucocorticoids have been shown to be released from the adrenal gland in a highly pulsatile, or ultradian, secretion mode. The dynamics of GR interaction with regulatory elements during these cycles was found to fluctuate in concert with the changes in extracellular hormone concentration. Transcription rates for GR target genes (determined by nascent RNA) were shown to vary markedly between ultradian and constant ligand treatment regimens, leading to the postulate that the ultradian mode of hormone secretion is required for biologically accurate regulation of gene targets by GR.